Documentation

Specify Property as Nontunable

Use the Nontunable attribute for a property when the algorithm depends on the value being constant once data processing starts. Defining a property as nontunable may improve the efficiency of your algorithm by removing the need to check for or react to values that change. For code generation, defining a property as nontunable allows the memory associated with that property to be optimized. You should define all properties that affect the number of input or output ports as nontunable.

Users of theSystem object™ can only change nontunable properties before calling the object or after calling the release function. In this example, you define the InitialValue property as nontunable and set its value to 0.

properties (Nontunable)
   InitialValue = 0;
end

Specify Property as Logical

Logical properties have the value, true or false. System object users can enter 1 or 0 or any value that can be converted to a logical. The value, however, displays as true or false. You can use sparse logical values, but they must be scalar values. In this example, the Increment property indicates whether to increase the counter. By default, Increment is tunable property. The following restrictions apply to a property with the Logical attribute,

properties (Logical)
   Increment = true 
end

Specify Property as Positive Integer

In this example, the private property MaxValue is constrained to accept only real, positive integers. You cannot use sparse values. The following restriction applies to a property with the PositiveInteger attribute,

properties (PositiveInteger)
   MaxValue
end
         

Specify Property as DiscreteState

If your algorithm uses properties that hold state, you can assign those properties the DiscreteState attribute. Properties with this attribute display their state values via the getDiscreteStateImpl when users call getDiscreteState. The following restrictions apply to a property with the DiscreteState attribute,

In this example, you define the Count property as a discrete state:

properties (DiscreteState)
   Count;
end

Complete Class Definition File with Property Attributes

classdef Counter < matlab.System
% Counter Increment a counter to a maximum value

  % These properties are nontunable. They cannot be changed 
  % after the setup method has been called or while the
  % object is running.
  properties (Nontunable)
      % The initial value of the counter
      InitialValue = 0
  end
  properties (Nontunable, PositiveInteger)
      % The maximum value of the counter
      MaxValue = 3
  end
  
  properties (Logical)
      % Whether to increment the counter
      Increment = true
  end
   
  properties (DiscreteState)
      % Count state variable
      Count
  end
      
  methods (Access = protected)
      % Increment the counter and return its value
      % as an output
  
      function c = stepImpl(obj)
          if obj.Increment && (obj.Count < obj.MaxValue)
              obj.Count = obj.Count + 1;
          else
              disp(['Max count, ' num2str(obj.MaxValue) ' ,reached'])
          end
          c = obj.Count;
      end
      
      % Setup the Count state variable
      function setupImpl(obj)
          obj.Count = 0;
      end
      
      % Reset the counter to one.
      function resetImpl(obj)
          obj.Count = obj.InitialValue;
      end
  end
end